This latest release candidate of the Clutter tool-kit brings performance improvements, a fix for a potential tearing problem, and various other bug-fixes. There isn't anything too exciting in this release, as we are just a release candidate or so away from seeing Clutter 1.0.0!
The release announcement for Clutter 1.0 RC3 can be found on the GNOME mailing list. Additional information on the Clutter Toolkit is available from their project web-site. One of the most prominent uses of Clutter to date is within the impressive Moblin V2 user-interface, but it's also being used within some of the GNOME Games.